Yep, the forums should have a search box.
Also see: http://photosynth.net/discussion.aspx?cat=01b6f15f-42eb-49cb-a221-ed56615e1c47&dis=448158ad-f2c9-4831-9871-fedd09ec0259
But as to using Google custom search... since Photosynth is a division of Bing, I'm thinking we'll not see a Google search box here. ^_~
I would more than welcome Photosynth.net search results to resemble Zune search results, though. For example, categorized results like:
Synths and Panos that matched your query:
Users who match your query:
Forum Topics that match your query:
Synths and Panos near locations on the map which match your query: